Thermal barrier coating with reduced edge crack initiation stress and high insulating factor

Abstract

A thermal barrier coating disposed on a substrate comprising a plurality of surface features formed on the substrate proximate an inner side of the substrate, each of the plurality of surface features comprising a metallic column having a top with rounded edges; a dense layer disposed in a valley located between each of the plurality of surface features, and the dense layer disposed on the top and covering the rounded edges; a thermally insulating topcoat disposed over the plurality of surface features.

What is claimed is: 
     
       1. A thermal barrier coating disposed on a substrate comprising:
 a plurality of surface features formed on said substrate proximate an inner side of said substrate, each of said plurality of surface features comprising a metallic column having a top with rounded edges; 
 a dense ceramic layer disposed in a valley located between each of said plurality of surface features, and said dense ceramic layer disposed on said tops and covering said rounded edges; the dense ceramic layer thickness tapers to zero over the rounded edges; 
 a thermally insulating topcoat disposed over the plurality of surface features; and 
 a bond coat disposed between the dense ceramic layer and the substrate. 
 
     
     
       2. The thermal barrier coating according to  claim 1 , wherein said dense ceramic layer comprises a 5-10 mil thick YSZ coating. 
     
     
       3. The thermal barrier coating according to  claim 1 , wherein said bond coat comprises a thickness of from 1-15 mil of MCrAIY. 
     
     
       4. The thermal barrier coating according to  claim 1 , wherein said thermally insulating topcoat comprises
 a porous material disposed over the dense ceramic layer between said plurality of surface features, and/or 
 disposed over the dense ceramic layer at the top of the metallic columns. 
 
     
     
       5. The thermal barrier coating according to  claim 4 , wherein said thermally insulating topcoat covers greater than 50 percent of a total area of the thermal barrier coating. 
     
     
       6. The thermal barrier coating according to  claim 1 , further comprising:
 the insulating topcoat includes an abradable layer that extends above the plurality of surface features. 
 
     
     
       7. The thermal barrier coating according to  claim 1 , wherein the dense ceramic layer disposed on said tops of the plurality of surface features is configured as dense vertically microcracked. 
     
     
       8. A gas turbine engine comprising:
 a compressor section; 
 a combustor fluidly connected with the compressor section; and 
 a turbine section downstream from the combustor, the turbine section having a seal that includes a substrate extending between two circumferential sides, a leading edge, a trailing edge, an inner side for resisting hot engine exhaust gases from the combustor, and an outer side, a plurality of surface features formed in said substrate protruding from said substrate away from said outer side, said plurality of surface features each comprising a metallic column having a rounded edge proximate a column top, a dense layer disposed in a valley between said plurality of surface features and disposed on said tops of said metallic columns, the dense ceramic layer thickness tapers to zero over the rounded edge; a thermally insulating topcoat disposed over the plurality of surface features and disposed over the dense layer; and a bond coat disposed between the dense layer and the substrate. 
 
     
     
       9. The gas turbine engine according to  claim 8 , wherein the plurality of surface features are configured as a pattern of rounded columns that define a cell structure therebetween; wherein the pattern provides the metallic columns a spacing that results in the plurality of surface features making up less than or equal to fifty percent of a coating area. 
     
     
       10. The gas turbine engine according to  claim 9 , wherein said plurality of surface features each comprise rounded edges at both the top and a bottom of the metallic column configured to reduce stress in the dense layer at both the tops and the bottoms of the metallic column of said plurality of surface features. 
     
     
       11. The gas turbine engine according to  claim 8 , wherein said thermally insulating topcoat comprises a porous material disposed over the dense layer between said plurality of surface features and disposed over the dense layer at the tops of the metallic columns. 
     
     
       12. The gas turbine engine according to  claim 8 , wherein said plurality of surface features include an aspect ratio of 0.5-2.5 height to width. 
     
     
       13. A process of interrupting spallation for geometrically segmented coatings on a gas turbine engine component comprising:
 said gas turbine engine component having a surface; 
 forming a plurality of surface features protruding from said surface, said plurality of surface features each comprising a metallic column having a rounded edge proximate a column top; 
 disposing a dense ceramic layer on said surface in a valley between said plurality of surface features and disposing said dense ceramic layer on said rounded edges and said tops of said metallic column, the dense ceramic layer thickness tapers to zero over the rounded edge; and 
 disposing a thermally insulating topcoat over said plurality of surface features; and 
 disposing a bond coat layer between the surface and said dense ceramic layer. 
 
     
     
       14. The process of  claim 13 , further comprising:
 configuring said plurality of surface features as a pattern of rounded columns that define a cell structure therebetween; wherein the pattern provides the metallic columns a spacing that results in the plurality of surface features making up less than or equal to fifty percent of a coating area. 
 
     
     
       15. The process of  claim 13 , wherein said plurality of surface features include an aspect ratio of 0.5-2.5 height to width. 
     
     
       16. The process of  claim 13 , further comprising:
 reducing stress in the dense ceramic layer at both the tops and a bottoms of the metallic columns of each of said plurality of surface features. 
 
     
     
       17. The process of  claim 13 , wherein said thermally insulating topcoat comprises a porous material disposed over the dense ceramic layer between said plurality of surface features, and/or disposed over the dense ceramic layer at the tops of the metallic columns.